This invention relates to a process for the production of custom-moulded ear inserts that are required for ear-level hearing aids and earmolds.
The shape of a custom ear insert is derived from an ear impression taken individually from the subject's ear. The ear impression is a negative replica of the ear.
There are currently two methods of impression shaping into custom ear inserts.
The older method is manual impression shaping. In this process, the impression is shaped manually by a technician with the use of mechanical cutters and grinders. The technician removes outer layers from the impression to achieve an insert shape suitable for a given custom product.
The newer method is computer-aided shaping of a digital ear image that is obtained by scanning of silicone impression, direct near scanning, CT scanning, MR1 scanning, or any volumetric imaging technique, and is further called a digital impression. In this process, the impression is virtually shaped with cutting and grinding tools available in the software.
Both the manual shaping and computer-aided modeling methods are time consuming, subjective, intuitive, and not free from inaccuracies. Inaccuracies in impression shaping result in ear inserts that have inadequate fit and are subsequently returned to the manufacturer with either a request for a new earpiece, or a request for a refund.
The template shaping method presented here offers an innovative approach to impression modeling. Unlike other methods, the shaping of the insert is done with a set of templates that have predetermined but adjustable curvatures. Anatomically accurate templates ensure superior fit of the resulting ear insert and eliminate common inaccuracies occurring in computer-aided modeling.